1. Field of the Invention
The present invention relates to a friction damper, and more particularly to a friction damper suitable for imparting an appropriate brake to an accelerator pedal, a brake pedal, a clutch pedal, or the like of a vehicle and a pedal device having the friction damper.
2. Description of the Related Art
Pedal devices, including an accelerator pedal, a brake pedal, a clutch pedal, and the like of a vehicle, are each comprised of a pedal disposed at an upper-limit position at which the pedal can be pressed down as well as an urging means consisting of a coil spring for urging the pedal in a direction in which the pedal returns to its upper-limit position when the pedal was pressed down.
In the case of the pedal device including an accelerator pedal, for example, as the accelerator pedal is pressed down, a throttle is opened or closed in the case of a gasoline engine, and a fuel injector is actuated in the case of a diesel engine. Conventionally, to open or close the throttle or actuate the fuel injector, the accelerator pedal and the throttle or the accelerator pedal and the fuel injector are linked together by an accelerator wire cable, and the accelerator pedal is adapted to pull the accelerator wire cable as it is pressed down.
Accordingly, when the accelerator pedal is pressed down, a reaction force (resisting force) of a value in which the resilient reaction force of the coil spring and the tensile reaction force of the accelerator wire cable are added together is applied to the accelerator pedal.
Meanwhile, fine control of fuel injection for the automotive engine is required for the purposes of low fuel consumption of vehicles and reduction of carbon dioxide, and electronic control of fuel injection such as the regulation of the throttle valve opening based on the pressing down of the accelerator pedal has been put to practical use.
In vehicles in which fuel injection of the engine is effected by electronic control, the accelerator wire cable arranged between the accelerator pedal and the throttle valve is normally omitted. With the vehicles without the accelerator wire cables, however, the reaction force with respect to the pedal pressing force differs in comparison with vehicles with the accelerator wire cables, and if a general driver who is accustomed to driving a vehicle with the accelerator wire cable drives the vehicle without the accelerator wire cable, there is a possibility of excessively pressing down on the accelerator, thereby consuming fuel more than before.
To obtain a large reaction force with respect to the pedal pressing force, if the spring force of a return spring for returning the pedal arm to the initial position of rotation is simply made large, there is a possibility of causing early fatigue to the pedal pressing foot due to the large reaction force from the return spring during constant traveling.
As a countermeasure for overcoming this problem, an arrangement has been proposed in which the pedal arm is linked to one end of a dummy cable passed through a fixed helical pipe, the other end of the dummy cable being terminated via a coil spring, to ensure that a reaction force exhibiting a hysteresis characteristic with respect to the pedal pressing force, which is similar to the conventional case in which the accelerator wire cable is provided, can be obtained by the dummy cable. However, since this countermeasure using the dummy cable requires a relatively large space for installing the dummy cable, this countermeasure can be adopted only in vehicles of large vehicle types, such as trucks and RVs, in which there is sufficient leeway in space. In addition, since various factors are involved, the adjustment of reaction force by using the dummy cable is relatively difficult, and there is a possibility of increasing the cost in order to set the reaction force to a desired value. Furthermore, although, in order to obtain the hysteresis characteristic, a metallic dummy cable is allowed to slide within the inner surface of a resin sheathing of the pipe so as to produce sliding resistance between the metallic dummy cable and the inner surface of the resin sheathing of the pipe, there is a possibility that a large change in the characteristic can occur due to the wear caused by this sliding over a long period of use.
The above-described problem occurs not only in the accelerator pedals, but can also occur in cases where appropriate rotational resistance is produced by using the above-described dummy cable or the like in brake pedals or clutch pedals, for example.
The present invention has been devised in view of the above-described circumstances, and it is an object of the present invention to provide a pedal device which makes it possible to simply set the hysteresis characteristic concerning the reaction force acting on the pedal to a desired value without using the accelerator wire cable and the dummy cable, as well as a friction damper suitable for use in the pedal device.
Another object of the present invention is to provide a pedal device which is capable of obtaining an appropriate reaction force with respect to the pedal pressing force, is capable of being installed compactly in comparison with the dummy cable, makes it possible to effect very simply the adjustment of reaction force having a hysteresis characteristic, and exhibits a small change in the characteristic, as well as a friction damper suitable for use in the pedal device.
Still another object of the present invention is to provide a friction damper which is capable of varying the magnitude of reaction force, and a pedal device using the friction damper.
A further object of the present invention is to provide a friction damper which is capable of varying the value of a resisting torque in correspondence with relative rotational displacement, and a pedal device using the friction damper.
To attain the above objects, in accordance with a first aspect of the present invention, there is provided a damper comprising: a hollow cylindrical member with a bottom; a movable member disposed in the hollow cylindrical member in such a manner as to be movable in an axial direction of the hollow cylindrical member but immovable about an axis of the hollow cylindrical member; a spring means disposed between the movable member and the bottom of the hollow cylindrical member, one end of the spring means abutting against the bottom of the hollow cylindrical member and another end thereof abutting against the movable member; a rotating member disposed in the hollow cylindrical member in such a manner as to oppose the movable member and to be relatively rotatable about the axis of the hollow cylindrical member; and a frictionally-resisting-force generating means for generating a frictionally resisting force to the relative rotation of the rotating member with respect to the hollow cylindrical member, and for causing the movable member to move away from the rotating member in the axial direction against the resiliency of the spring means and to approach the bottom of the hollow cylindrical member so as to increase the spring force of the spring means, thereby increasing the frictionally resisting force.
Furthermore, to attain the above objects, in accordance with a second aspect of the present invention, there is provided a friction damper comprising: an inner member extending like a shaft; a tubular outer member disposed coaxially with the inner member and on an outer side of the inner member; a frictionally engaging means provided in an annular space on a radially outward side of the inner member and on a radially inward side of the outer member; a resilient means provided in the annular space; an urging-force varying means provided in the annular space, wherein the frictionally engaging means has a first portion which rotates integrally with the inner member and a second portion which rotates integrally with the outer member and is provided in such a manner as to be capable of coming into contact with the first portion in the axial direction, wherein the resilient means is arranged to urge the first portion and the second portion in a direction in which the first portion and the second portion are brought into contact with each other and are pressed against each other, and wherein the urging-force varying means is arranged to make variable an urging force of the resilient means in correspondence with a relative rotational displacement of the inner member and the outer member.
In accordance with the friction damper according to the second aspect of the invention, when a relative rotational displacement occurs between the inner member and the outer member, the urging force of the resilient means for pressing the first portion and the second portion against each other is varied by the urging-force varying means.
In the friction damper in accordance with a third aspect of the invention, in the friction damper according to the second aspect, a shaft inserting hole extending in the axial direction is penetratingly formed in a center of the inner member.
In the friction damper in accordance with a fourth aspect of the invention, in the friction damper according to the second or third aspect, a flange portion projecting radially outward is formed at an axial end of the inner member, and the first portion is formed by the flange portion.
In the friction damper in accordance with a fifth aspect of the invention, in the friction damper according to any one of the second to fourth aspects, a friction plate which rotates integrally with the inner member is provided in the annular space in such a manner as to be movable in the axial direction, and the first portion is formed by the friction plate.
In the friction damper in accordance with a sixth aspect of the invention, in the friction damper according to any one of the second to fifth aspects, the outer member has a hollow cylindrical portion, a longitudinal end of the hollow cylindrical portion is formed as an open end which is open, a flange portion projecting radially inward is formed at another longitudinal end of the hollow cylindrical portion, and the second portion is formed by the flange portion.
In the friction damper in accordance with a seventh aspect of the invention, in the friction damper according to any one of the second to sixth aspects, a friction plate which rotates integrally with the outer member is provided in the annular space in such a manner as to be movable in the axial direction, and the second portion is formed by the friction plate.
In the friction damper in accordance with an eighth aspect of the invention, in the friction damper according to any one of the second to seventh aspects, the resilient means is disposed between the frictionally engaging means and the urging-force varying means in the annular space, and the urging-force varying means is arranged to change an axially extending space for accommodating the resilient means, in correspondence with the relative rotational displacement of the inner member and the outer member.
In the friction damper in accordance with a ninth aspect of the invention, in the friction damper according to any one of the second to eighth aspects, the urging-force varying means is provided with a restricting means for restricting the movement of the urging-force varying means in a direction away from the frictionally engaging means.
In the friction damper in accordance with a 10th aspect of the invention, in the friction damper according to the ninth aspect, the urging-force varying means is provided with an annular inner variable member joined integrally to the inner member, an annular outer variable member disposed in such a manner as to oppose the inner variable member and joined integrally to the outer member, a cam portion formed on a surface of the inner variable member opposing the outer variable member, and a cam portion formed on a surface of the outer variable member opposing the inner variable member, the cam portions being arranged to change a distance between the inner variable member and the outer variable member in the axial direction in correspondence with the relative rotational displacement of the inner member and the outer member.
In the friction damper in accordance with an 11th aspect of the invention, in the friction damper according to any one of the second to eighth aspects, the urging-force varying means is formed by a variable member which is threadedly joined to one of the inner member and the outer member, and is joined to another one of the inner member and the outer member in such a manner as to be unrotatable but movable in the axial direction.
In the friction damper in accordance with a 12th aspect of the invention, in the friction damper according to any one of the second to 11th aspects, the inner member is joined to a rotating shaft in such a manner as to be rotatable integrally with the shaft, the outer member is unrotatably joined to a member which rotatably supports the shaft, and the second portion is unrotatable together with the outer member.
Furthermore, to attain the above objects, in accordance with a 13th aspect of the present invention, there is provided a pedal device for a vehicle, comprising: a pedal arm which is rotatably supported by a supporting frame; a first spring means for rotatively urging the pedal arm to an initial position of its rotation; and a damper for imparting a resisting force to the rotation of the pedal arm, wherein the damper includes: a hollow cylindrical member with a bottom; a movable member disposed in the hollow cylindrical member in such a manner as to be movable in an axial direction of the hollow cylindrical member but immovable about an axis of the hollow cylindrical member; a second spring means disposed between the movable member and the bottom of the hollow cylindrical member, one end of the spring means abutting against the bottom of the hollow cylindrical member and another end thereof abutting against the movable member; a rotating member disposed in the hollow cylindrical member in such a manner as to oppose the movable member and to be relatively rotatable about the axis of the hollow cylindrical member; and a frictionally-resisting-force generating means for generating a frictionally resisting force as the resisting force to the relative rotation of the rotating member with respect to the hollow cylindrical member, and for causing the movable member to move away from the rotating member in the axial direction against the resiliency of the second spring means and to approach the bottom of the hollow cylindrical member so as to increase the spring force of the second spring means, thereby increasing the frictionally resisting force, and wherein the rotation of the pedal arm is transmitted as the relative rotation of the hollow cylindrical member and the rotating member.
In accordance with the pedal device according to the 13th aspect, when the rotating member is relatively rotated with respect to the hollow cylindrical member due to the rotation of the pedal arm based on the pressing down of the pedal, an increasing frictionally resisting force is generated by the frictionally-resisting-force generating means. On the other hand, when the pressing down of the pedal is canceled and the rotating member is relatively reversely rotated with respect to the hollow cylindrical member, the frictionally resisting force in the frictionally-resisting-force generating means becomes small. Consequently, by virtue of the frictionally resisting force having this hysteresis characteristic, a resisting force similarly having the hysteresis characteristic is imparted to the rotation of the pedal arm. This resistance force makes it possible, for instance, to prevent the accelerator pedal from being excessively pressed down, which can otherwise consume fuel more than before.
In the pedal device for a vehicle in accordance with a 14th aspect of the invention, in the pedal device according to the 13th aspect, the frictionally-resisting-force generating means has a projection formed integrally on one surface of the rotating member, opposing the movable member, in such a manner as to project in the axial direction toward one surface of the movable member and a projection formed integrally on the one surface of the movable member, opposing the rotating member, in such a manner as to project in the axial direction toward the one surface of the rotating member, the projections being arranged to come into planar contact with each other.
In the pedal device in accordance with the 14th aspect, since the frictionally-resisting-force generating means is formed by projections which are disposed between the movable member and the rotating member and are formed integrally to the movable member and the rotating member, respectively, the pedal device can be made very compact, and can be installed by making effective use of a small space. Moreover, since the projections are brought into planar contact with each other, the coefficients of friction at the contact surfaces can be set appropriately, thereby making it possible to determine a resisting force having a hysteresis characteristic which can be imparted to the rotation of the pedal arm, and making it possible to effect the adjustment of the reaction force very simply.
In the pedal device for a vehicle in accordance with a 15th aspect of the invention, in the pedal device according to the 13th or 14th aspect, the frictionally-resisting-force generating means has an inclined surface formed on the one surface of the rotating member opposing the movable member, and an inclined surface formed on the one surface of the movable member opposing the rotating member and arranged to come into planar contact with the inclined surface formed on the one surface of the rotating member.
In accordance with the pedal device in accordance with the 15th aspect, by appropriately setting the coefficients of friction at the inclined surface formed on the one surface of the rotating member and at the inclined surface formed on the one surface of the movable member opposing the rotating member, it is possible to determine in the frictionally resisting-force generating means the resisting force with the hysteresis characteristic which can be substantially imparted to the rotation of the pedal arm, so that the adjustment of the reaction force can be effected very simply.
In the pedal device for a vehicle in accordance with a 16th aspect of the invention, in the pedal device according to any one of the 13th to 15th aspects, the frictionally-resisting-force generating means has a fixed surface which comes into planar contact with another surface of the rotating member.
In the pedal device in accordance with the 16th aspect, since it is possible to determine the resisting force with the hysteresis characteristic which can be substantially imparted to the rotation of the pedal arm by appropriately setting the coefficients of friction at the other surface of the rotating member and the fixed surface, the adjustment of the reaction force can be effected very simply in the same way as the pedal device in accordance with the 15th aspect.
It should be noted that, in the pedal device in accordance with the 16th aspect, the other surface of the rotating member and the fixed surface which are brought into planar contact with each other may be formed by inclined surfaces in the same way as the pedal device in accordance with the 15th aspect.
In the pedal device for a vehicle in accordance with a 17th aspect of the invention, in the pedal device according to the 16th aspect, the fixed surface is formed on the hollow cylindrical member.
In the pedal device in accordance with the 17th aspect, since the fixed surface is formed on the hollow cylindrical member, the pedal device can be formed more compactly. It goes without saying that the fixed surface may be formed on the supporting frame or the pedal arm, instead of being formed on the hollow cylindrical member.
In the pedal device for a vehicle in accordance with an 18th aspect of the invention, in the pedal device according to any one of the 13th to 17th aspects, the bottom of the hollow cylindrical member can be adjustably positioned in the axial direction.
In the pedal device in accordance with the 18th aspect, since the bottom of the hollow cylindrical member can be adjustably positioned in the axial direction, the initial resilient force generated by the second spring means, i.e., the initial resisting force, can be adjusted and set arbitrarily, so that an optimum initial resisting force can be obtained.
In the pedal device for a vehicle in accordance with a 19th aspect of the invention, in the pedal device according to any one of the 13th to 18th aspects, the second spring means has at least two coil springs arranged concentrically, and the at least two coil springs have mutually different moduli of elasticity.
As the second spring means, a spring means using such as rubber or a leaf spring may be used. Preferably, if the second spring means is formed by at least one coil spring, the pedal device can be made to excel in durability and simple in the structure. In addition, if the second spring means is formed by at least two coil springs having mutually different moduli of elasticity as in the case of the pedal device in accordance with the seventh aspect, one coil spring can be used for fine adjustment, and the design and adjustment of the resisting force can be effected simply. Hence, such an arrangement is very preferable from this standpoint.
In the pedal device for a vehicle in accordance with a 20th aspect of the invention, in the pedal device according to any one of the 13th to 19th aspects, the pedal arm is an accelerator pedal arm.
In the pedal device for a vehicle in accordance with the present invention, an arrangement may be provided such that the rotation of the pedal arm is transmitted to either the hollow cylindrical member or the rotating member. Preferably, however, the rotation of the pedal arm is arranged to be transmitted to the rotating member, in which case, the hollow cylindrical member is fixedly supported by the frame. In the case where the rotation of the pedal arm is arranged to be transmitted to the hollow cylindrical member, the rotating member is fixedly supported by the frame.
Furthermore, to attain the above objects, in accordance with a 21st aspect of the present invention, there is provided a pedal device comprising: a rotating shaft supported by a supporting frame; an accelerator pedal which is disposed at an upper-limit position where the accelerator pedal can be pressed down and which swings about the rotating shaft; a resisting means for generating resistance in a direction in which the pressing down of the accelerator pedal is hampered when the accelerator pedal is pressed down; and an urging means for urging the accelerator pedal in a direction in which the accelerator pedal returns to the upper-limit position when the accelerator pedal is pressed down at the upper-limit position; wherein the resisting means is formed by a friction damper in which a portion which rotates by following the swinging motion of the accelerator pedal comes into contact with a stationary portion so as to generate resistance.
In the pedal device in accordance with a 22nd aspect of the invention, in the pedal device according to the 21st aspect, the rotating shaft is supported by mutually opposing portions of the supporting frame, and the friction damper is disposed in a space between the mutually opposing portions of the supporting frame.
In the pedal device in accordance with a 23rd aspect of the invention, in the pedal device according to the 21st or 22nd aspect, the friction damper is disposed coaxially with the rotating shaft.
In the pedal device in accordance with a 24th aspect of the invention, in the pedal device according to any one of the 21st to 23rd aspects, the friction damper is arranged to generate torque of a fixed value irrespective of displacement in the swinging motion of the accelerator pedal.
In the pedal device in accordance with a 25th aspect of the invention, in the pedal device according to any one of the 21st to 23rd aspects, the friction damper is arranged such that the value of torque changes in correspondence with the displacement in the swinging motion of the accelerator pedal.
In the pedal device in accordance with a 26th aspect of the invention, in the pedal device according to the 21st aspect, the rotating shaft is rotatably supported by the supporting frame and is provided so as to rotate in interlocked relation to the swinging motion of the accelerator pedal, wherein the friction damper is disposed coaxially with the rotating shaft and includes an inner member into an interior of which the rotating shaft is inserted and which rotates integrally with the rotating shaft coaxially therewith, a tubular outer member disposed coaxially with the inner member on an outer side of the inner member in such a manner as to be unrotatable, a frictionally engaging means provided in an annular space on a radially outward side of the inner member and on a radially inward side of the outer member, and a resilient means provided in the annular space, wherein the frictionally engaging means has a first portion which rotates integrally with the inner member and a second portion which is unrotatable and is provided in such a manner as to be capable of coming into contact with the first portion, and wherein the resilient means is arranged to urge the first portion and the second portion in a direction in which the first portion and the second portion are brought into contact with each other and are pressed against each other.
In the pedal device in accordance with a 27th aspect of the invention, in the pedal device according to the 21st aspect, the rotating shaft is rotatably supported by the supporting frame and is provided so as to rotate in interlocked relation to the swinging motion of the accelerator pedal, wherein the friction damper is disposed coaxially with the rotating shaft and includes an inner member into an interior of which the rotating shaft is inserted and which rotates integrally with the rotating shaft coaxially therewith, a tubular outer member disposed coaxially with the inner member on an outer side of the inner member in such a manner as to be unrotatable, a frictionally engaging means provided in an annular space on a radially outward side of the inner member and on a radially inward side of the outer member, a resilient means provided in the annular space, and an urging-force varying means provided in the annular space, wherein the frictionally engaging means has a first portion which rotates integrally with the inner member and a second portion which is unrotatable and is provided in such a manner as to be capable of coming into contact with the first portion, wherein the resilient means is disposed between the frictionally engaging means and the urging-force varying means in the annular space and is arranged to urge the first portion and the second portion in a direction in which the first portion and the second portion are brought into contact with each other and are pressed against each other, and wherein the urging-force varying means is arranged to change an axially extending space for accommodating the resilient means, in correspondence with the relative rotational displacement of the inner member and the outer member.
In the pedal device in accordance with a 28th aspect of the invention, in the pedal device according to any one of the 21st to 27th aspects, the resisting means includes the urging means.
In the pedal devices in accordance with the 21st to 28th aspects of the invention, the resisting means is formed by a friction clutch, and the adjustment of increase or decrease of resistance occurring in the friction clutch can be made easily, so that the hysteresis characteristic in the pedal device can be easily set to a desired value.
It should be noted that the pedal arm in the device of the present invention is preferably the aforementioned accelerator pedal arm, but the pedal arm is also applicable to a brake pedal arm, a clutch pedal arm, or the like.
In accordance with the friction damper of the present invention, the value of torque can be varied in correspondence with the relative rotational displacement of the inner member and the outer member. Accordingly, the friction damper of the present invention can be used at a location where the value of torque is to be varied in correspondence with the relative rotational displacement of the inner member and the outer member.
In accordance with the pedal device of the present invention, it is possible to obtain an appropriate reaction force with respect to the pedal pressing force, the pedal device can be installed compactly in comparison with the dummy cable, and the adjustment of reaction force having a hysteresis characteristic can be made very simply.
In addition, in accordance with the pedal device of the present invention, the hysteresis characteristic can be simply set to a desired value without using a cable.